Magnetic recording apparatus



March 7, 1950 J, WALKER 2,499,895

MAGNETIC RECORDING APPARATUS Filed Oct. 8, 1945 3 Sheets-Sheet l as a9 2;,

LA 14 n Z0 Z9 47 56 45 INVENTOR.

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-Wza/M MM March 7, 1950 J. B. WALKER MAGNETIC RECORDING APPARATUS 3 Sheets-Sheet 2 Filed Oct. 8, 1945 5 mm H K N I l E VM 0 W F 5 4 W March 7, 1950 J. B. WALKER 2,499,895

MAGNETIC RECORDING APPARATUS Filed Oct. 8, 1945 3 Sheets-Sheet 5 ATTOEA/EKi.

Patented Mar. 7, 1950 UNITED STATES PATENT OFFICE MAGNETIC RECORDING APPARATUS Joseph B. Walker, Hollywood, Calif.

Application October 8, 1945, Serial No. 620,920

7 Claims.

This invention relates to magnetic recording apparatus which embodies a tape magazine adapted to house a pair of rotatable spools between which a considerable length of steel tape or wire may be carried for transferal from one spool to the other through a structurally separate magnetic unit operable to, selectively, record on the tape or wire, or transcribe or erase therefrom magnetic impressions corresponding to sound vibrations.

While the principles involved in, and the essential structural elements required for, magnetic recording are well known in the art, the utility and commercial success of prior art equipment of this type has been restricted, due largely to difficulties encountered and the care required incident to assembling and disassembling the reels of tape in operative relationshipwith the magnetic head for recordation and transcription. Steel tape of the type adapted for practical utility in magnetic recording apparatus must be very thin to provide the required flexibility, and particularly to obviate excessive bulk. Tape of this type, however, is also very frangible, and also, because of its tendency to coil when loose, is extremely difiicult to handle.

It has been found that the most effective ma netic recording system is that which contemplates passing the magnetic field through the tape by pole pieces disposed on opposite sides of the tape, and the adjustment of the pole pieces in this form of recording is highly critical. This necessitates threading the tape of each successive reel to be used between the pole pieces, which operation is time consuming, with the ever present danger of breaking the tape as a result of careless handling.

It is a general object to provide a compact, portable and inexpensive magazine, structurally separate from the recording head and power mechanism, in which a quantity of steel tape is protectively enclosed, while permitting the impression of a magnetic record upon any reach of the tape or the transcription or erasure from the tape of any part of a previously-recorded magnetic pattern without removal of the tape from the magazine.

More specifically, an object hereof is to provide guide means for a pair of magnetic pole pieces, one of which comprises an integral part of the magazine in which the record medium is encased, whereby electrical or magnetic contact may be eifected to energize the poles magnetically to opposite polarity and coincidentally critically position said poles at opposite sides of the 2 recording medium for most efiective recording and transcription.

Another object is to provide a magazine having a pair of tape reels journalled therein, to either of which power may be selectively applied for shifting the tape from one reel to the other, in combination with guide mechanism for directing a length of tape adjacent an opening in the magazine for operative engagement by an electromagnet, energized by a signal current, of a separate recording, transcribing or erasing unit with which the magazine may be releasably associated.

Another object hereof is to provide one or more pole pieces movable laterally relative to a plane in whichthetape travels while being transferred from one reel to the other, the pole or poles being shifted into operative contact with the tape in response to resilient means actuated by an element of the recording unit with which the magazine is associated, for transcription or recordation or the erasure of a previously recorded signal from the tape.

still another object is to provide brake mechanism for the spools to normally hold the reels against rotation so as to maintain taut the reach of the tape extending therebetween, and thus facilitate the assembly of the magazine with the recording unit, and particularly obviate any tendency toward snapping the tape when power is applied, the brake mechanism being automatically released incident to association of the magazine with the recording unit.

Other objects are the provision of an assembly wherein the relationship between the pole pieces and tape is effected automatically, the operator being required onl to place the magazines in proper juxtaposition with the base of the recording unit, and further to provide inherent means for maintaining the requisite pressure of the pole pieces upon the tape during recordation and transcription, as well as simplicity of construction, economy of manufacture, and durability.

In the drawings:

Fig. 1 is a longitudinal sectional view through the casing, illustrating the internal construction;

Fig. 2 is a sectional view similar to Fig. 1, depicting the magazine in operative relation with the base of a recording unit, and illustrating the position and function of the various parts of the magazine as affected by the recording unit;

Fig. 3 is a perspective view of the pole piece assembly, and the support and guiding means Referring to the drawings in detail, the.

numerals of which indicate similar parts throughout the several views, IQ designates a flat elongated casing rectangular in both longitudinal and transverse crosssection. A pair ofspools I I and I2 are mounted in opposite ends of casing ID:

on a pair of spindles I3 journalled in opposed side walls of the casing. One side of casinglilis' provided with a pair of holes which are aligned, respectively, with-spindles I3, the corresponding ends of which are formed with keyi-ways I4 for selective engagement by a drive shaft (not shown) associated with a recording unit hereinafter more indetail referred to. Thus, either of spools II and- I2 may be drivento draw tape I5 from the other spool, which idles in response to tension upon-the tape. Opposite ends of tape I5 are permanently attached to the hubs I6 of the respective spools II and I2 b means not shown. Suitable mechanismwell known in the art may be incorporated within the magazine to limit the number of rotations of each of the spools. so as to preventfracture of tape I5 when the supply on either spool is exhausted. The length of tape I5 extending-between the spools I I and iZpasses over a pair of idler pulleys Iijournalled in close proximity to the bottom I8 of the case, so as to support the intermediate reach of tape closely adjacent the bottom IS in which an elongated opening I9,- equi-spaced from theends of casing I0, is formed.

A generally T-shaped. plate 2G-is secured in inverted position by means about to be described on one side of easing) withthe intersection of itselements disposedadjacent the opening, IS in bottom It of the casing. The lateral projections of plate Ell'are each formed'with a slot 2| through each of which a screw 22"extends. The slots ZI are in parallel relation, and screws 22 are threaded into the side wall of the casing so as to maintain plate against'vertical movement but permit slidable movement parallelto bottom I8 of the casing. Superimposed upon the vertical section of plate Zflis -asecond fiat rectangular plate 23, formed with a pair ofcentrallylocated slots 24 which are arranged parallel to the longitudinal axis of plate 23. The plates 20 and 23'are secured together against relative lateral movement by means of screws 25 projecting through slotsfi l and threaded into plate-2G. The T-shaped plate 23. and plate 23 carried thereby are normally drawn to the right as seen in Figs. 1 and 2 by a helical spring 26, having its ends connected between one end of casing'ID andplate 20.

A small flat iron bar 21, having one end secured to and preferably insulated from, the lower end of plate 23 projects laterally therefrom to" the middle plane of the casing so as to overhang the reach of tape I5 disposed opposite the opening I9. Slots '24 in plate 23 through which the screws 25 extend are of a length sufiicient to permit the pole piece 2Tto contact tape I5 during operation and to be'withdrawn from such engagement when the magazine is not associated with its recording unit. To this end a helical spring 28 is provided for connection between the upper end of plate 23 and the top of the casing, which normally suspends, resiliently, the plate 23 and its pole piece 2'! in an elevated position. The lower edge of pole piece 2'! is cut away adjacent its outer end to form, at the outer extremity of the pole, a tape contact 29 of the required size and shape. In each of the embodiments with the exception of that shown in Fig. 4, no coil is directly associated with the magazine pole piece, the latter being magnetically charged by a coil carried by the recording unit, as is hereinafter described.

Each of spools I I and I2 is provided with brake mechanism comprising a flat angle 30 disposed inoppositeupper. corners of casing IE1, opposite sides of each angle 30 being normally disposed substantially parallel with the top and adjacent end of the casing. Theupper side of each angle 3flis'pivoted on a'pin 3| having its ends secured in the'sides of the casing above theadjacent spool, wherebythe angle 30;.being ofiset laterally with respect'to the spool, is freeto' pivot within the limitspermitted by the end and top of thecasing. Each angle 30'is formed with a Web 32 having a laterally-projecting brake shoe 33 adapted to extend into the arc of. the periphery of the adjacent spool when the lower end of angle 38' is swung toward the middle of thecasing so as to frictionally engagethe spool.

The upper side-of. each angle 38 is provided with an arcuate spring extension 34 which bears on the upper'end of the vertically-sliding plate 23. With the magazine out of association :with the recording unit, and with the plate 23 held in elevated position in response to the tension of spring 28, the angles 30. are maintained in a position'with the laterally'projecting brake shoe 33 in engagement with the spools I I and I2, as seen in Fig. 1.

In order to assureproper alignment of the pole pieceZI with a-pole piece later-to be described carried by therecordingunit, I provide an angle bracket 35-secured to the lower endof plate 20 at'a pointlaterally offset with respect to plate 23. One side of bracket 35 projects-outwardly from plate 20 for releasable engagement by an upstanding guidemember' 36 securedto the'recording unit (see Fig. 2) about to'be described.

The recording unit comprises a base 3'! on which blocks 38 are secured in-spaced relation for the support of casing. ID of the magazine. A bolt 39 projecting upwardly from each block 38 is adapted toengage in. one ofa pair of.slotted lugs 40 carriedby the respectiveends of'the casing ID. A knurled nut 4| for each of'bolts 39 provides a means for clampingthe magazine firmly onto base3'l in properly adjusted position. In order to further assureproper alignment of the magazine and recording unit,- a pair of openings 42 are formed in opposite ends of bottom I8 of casing I0 to'register with tapered dowel pins 13 mounted in therespective blocks'38 ofbase 37. The lower end of each of the brake-lever angles is formed with a laterally'projectin'g foot which normally extends over one of the openings :22'provided for the accommodation of the complementary dowel pin'43. Each of dowel'pins 43 is of a length suificient to engage one of feet 44 of the brakelever angles 30 within the magazine incident to the operation of assembling the magazine upon the recording'unit so as to displace the brake shoe 33from the'adjacent spool and permit rotationof the latter upon'th'eapplication of power to the take-up spool. The tilting of the brake-lever angles in response to lowering the magazine over the dowel pins 43 depresses the arcuate springs 34 attached to the upper sides of levers 30. The pressure exerted by the springs 34 on the upper end of plate 23 overcomes the tension of the helical spring 28 by which the plate is normally held in suspended position so as to lower the pole piece 21 of the magazine against the upper surface of tape 15.

The upper end of the guide member 36, mounted on base 31 intermediate blocks 38 and above generally alluded to, is beveled, as at 45, to engage the lower edge of the laterally-projecting side of the angle 35, which is normally held by spring 28 in a position where it will abut against the beveled end 45 of guide member 36 upon lowering of the casing over dowel pins 43. As the magazine is lowered onto base 31, bracket 35 is compelled to shift laterally, in response to the urge of the upper end of guide member 36, imparting this motion to plates 26 and 23 against the tension of spring 26. Continued downward movement of the magazine lowers the laterally-shifted angle bracket 35 on one side of the guide member 36 with which. it is maintained in firm contact by spring 26. Thus pole piece 2? of the magazine carried by plate 23 is positively located in a predetermined position relative to guide member 36 and associated elements of the recording base 31.

Mounted on base 31 intermediate dowel pins 43 by suitable means is an axially vertical coil 46, having a core 4! adapted to project slightly above base 31 so as to contact the underside of tape l5 when the magazine is clamped in position. The lower end of core 41 is formed with a radial extension 48 from the outer end of which upwardly projects a contact element 49 terminating at a point considerably above coil 46 and. pole piece 56 of opposite polarity projecting upwardly from coil 46. The upper end of contact element 49 is tapered as at 5| in the same manner as is the guide member 36 for engagement with pole piece 21 carried by the plate 23 of the magazine when the latter is assembled with the recording unit. Thus it will be seen that the upright contact element 49 performs initially the same function as guide member 36, i. e., of shifting plate 23 laterally within the magazine to properly align the pole pieces 21 and 56. As the contact element 49 is the same thickness as the pole piece 50, it will thus be observed that the two pole pieces, on opposite sides of the tape, are in offset relation, their opposite side surfaces lying in the same plane. engagement between the contact element 49 and pole piece 2'! incident to the tension of spring 26, the polarity of the lower end of core 41 of coil 46 is transmitted to the pole piece 2! within the magazine. Due to the offset relationship of the pole pieces 21 and 56 on opposite sides of tape 1 5, the magnetic field set up upon energization of coil 46 is confined to a small area of tape l5 between the opposedcorners of the respective pole pieces, and objectionable magnetic flux is reduced to a minimum.

Windows (not shown) may be provided in either or both sides of easing I 0 by which the operator may observe the amount of tape on each spool. Power may be transmitted to either of spools II or l2 through their spindles I3 by a flexible drive (not shown) from an appropriately located motor, or by any other conventional mechanism.

In Fig. 4 I have illustrated a modified form of As a result of the firm coil and pole piece assembly. In this embodiment each pole piece 52 is provided with a separate coil 53 which is secured by suitable means (not shown) to base 31 and plate 23 of the magazine respectively, whereby the pole pieces 52 are supported in direct opposition to one another at opposite sides of tape I5 when the magazine is assembled with the recording unit. To this end the guide member 36 and angle 35 are positioned to critically shift plates 26 and 23 and thereby efiect the required juxtaposition of the pole pieces 52. The ends of the coil 53 within the magazine are connected to a pair of resilient contacts 54 suitably mounted to the bottom of casing I!) which are adapted to engage complementary contacts 55 carried by base 31 and connected to a source of electricity through the stationary coil 53 in an obvious manner.

In Figs. 5 and 6 I have illustrated a simplified embodiment of the magazine of my invention, wherein the lateral movement of the magazine pole pieces 21 and 56 is dispensed with. A plate 23 is slidably carried directly by the side of the casing by screws 25 which extend through the vertically-aligned slots 24 in plate 23 and are threaded into the casing. In other particulars, the magazine is substantially the same as that hereinabove described. The recording unit with which the magazine of the embodiment shown in Fig. 5 is adapted to cooperate comprises a base 31 adjacent the ends of which blocks 38 are mounted for the support of the magazine when recording, transcription or erasure of a previously recorded magnetic pattern is desired. Between blocks 38 a slidable carrier 56 is superimposed upon supporting base 37 being connected thereto by screws 51 extending through slots 58 in carrier 56 which limit the degree of movement of the carrier and confine the direction of that movement to a plane parallel with the magazine when the latter is connected to the base. A helical spring 59 has its ends connected to carrier 56 and to one of blocks 38 so as to normally maintain carrier 56 at one end of its range of movement. The guide member 35 adapted to engage angle bracket 35 which, in the embodiment under consideration, is secured directly to the side of easing l6 rather than to a plate 26, which is omitted in this embodiment, is mounted on carrier 56 by suitable means not shown. The coil assembly 46 illustrated in Fig. 2 is mounted on carrier 56 and has associated therewith a contact element 49 for transmitting the magnetic energy from the lower end of core 4'! of the coil to pole piece 27 of the magazine. With the carrier 56 disposed at the end of its range of movement, as limited by the screws 51, in response to the tension of spring 59, the contact element 49 of the coil 46 and the guide member 36 will be only slightly misaligned in the opposite direction with respect to pole piece 2! of the magazine and angle bracket 35 respectively, when the magazine is in position for lowering onto dowel pins 43. As the upper ends of contact element 49 and guide member 36 are beveled on the side opposite to which the carrier may be moved against the tension of the spring 59, continued lowering of the magazine onto base 3? compels carrier 56 to shift and complete the misalignment of guide member 36 and contact element 49 with their respective complementary parts of the magazine. The tension of spring 59, however, maintains an effective contact between the element 49 and upper pole piece 21, assuring the operator that by merely clamping the magazine to the base the :lowing claims, the :term where otherwise indicated, is employed toidesig- 7 p01e= pieces? 21;.aand 50rof thefrecording unit and magazine, respectively, :will :be :properly :posi- *tione'd'and in contactswith tapell5. Asin the embodiment ofFigs. 1-4, the brake mechanism for spools H and l2.isre1eased'by dowelpins 43 coincident with .the :assembly :of the :magazine with the recording .base :for operation.

Itwill thus:be seenthat I have-provideda compact, magnetic recording unit comprising a magazineof novel construction capable of: quick assembly and ;:disassembly with the recording basewhereby any: reach ofthe tape orwire," per- :manently and protectively housed'within the magazine, may :bebrought into contact with the recording head for yrecordation "or transcription without the necessitysofthreading theltape between the pole 'piecesioftthe magnets and completely obviating all'smanual adjustment of the recording mechanism preliminary to actual recordation, transcription, or the erasure of a previously recorded signal.

While only a single composite recording head .isidisclosed in each of the three embodiments, .it will be appreciated that separate erasing mag- .netstmay be associated with the magazine and recording unit, in precisely the same manner as are the coil assembly and pole pieces of any'of the several structures for actuation in the same manner, without specific illustration or further description.

In the foregoing description and in the folrecording, :except nate transcribing and erasing..as Well, and, correspondingly, inthose claims contemplating a single coil assembly and/or tape orrecording .medium, the language is to be interpreted as :capableof recordation, transcription orerasure of a magnetic pattern upon either a tape or wire.

The several embodiments shown in the drawings and hereinabove described being merely illustrative of' my invention, it will be understood that'numerous .changes in size, design, shape, number and proportion of the parts :may be made, that in each ofxthe embodiments with the exception of that shown in Fig. .4, .theguide member36. and angle bracket 35 maybe omitted ifldesiredcand thatpineachof the embodiments .thetmechanism by which the pole piece Within the magazine is displaced'from the tape upon .disassociation of themagazine from the record- 'ing. unit,1may be vomitted, whereby the pole piece will remain incontact with the inner surface of the tape at all times,all without departing from the spirit of my invention as defined in the appended claims.

What I claim and desire to secure by'Letters Patent is:

1.In apparatus of the character described, a

magazine having an opening therein, 'a pair of spools journalled within said magazine at oppo- -si-te sides,- respectively, of said opening for carrying'a recording medium therebetween, guide means to retain a reach of said recording medium adjacent said opening, a pole piece avithin said magazinein contact with said recording mediimi, a recording unit comprising a pole piece disposed exteriorly of said'magazine,

and means to operatively position said pole pieces on opposite sides ofv the recording medium operable incident to positioning said magazine :OIl said; recording unit.

.2. 'In apparatus; of the character described, 'a

ma'gazine having an opening :therein, means r. said -magazine to support L and nmove -::a,

ing medium in operative opposition to said first pole piece, and means carried by said magazine and recording unit operable upon actuation of said guide means to shift said first-named pole piece into contact with said recording medium.

5 3. In apparatus of the character described,'a

magazine having an opening therein, means within said magazine to support and move a re- .cordingmedium adjacent said opening, a pole piece within said magazine to contact one side of the recording medium, a recording unit disposed exteriorly of the magazine comprising a second pole piece, guide means carried by said magazine and recording unit adapted for engagement upon assembly of the magazine and 25 recording unit to operatively juxtapose said second pole in contact with the opposite side of said recording medium, and means to energize the pole piece in said magazine operable coincident with the association of the magazine and recording unit.

4. In apparatusof the character described, a magazine having an opening therein, a recording--medium,-means to move said recording medium-withinsaid magazine adjacent said opening, a; pole piece within said magazine, a base for-supporting said-magazine, a second pole .piece carriedzby said .base, and means operable in response to positioning said magazine upon -.said base to'shiftsaid pole pieces relative to t; one another for operative juxtaposition with .zsaidzrecording medium.

5., lniapparatusof' the character described, a .-;magazine"having an opening therein, a recording medium within said magazine movable' adjacent said'opening, a pole piece within said -magazine-in contact with one surface of the recording-medium, a base, a second pole piece carried by. said base, meansto mount said magazine-onesaid ,base,.and means to shift said sec- 0nd :pole-piece longitudinally of the recording medium .incident to mounting said magazine upon'said base.

;6... In."apparatus of the'character described, a -magazine havingzzan. opening therein, a record- ;,;;ing mediumwithin saidmagazine movable ad- :jacentsaid opening, a 'pole piece within said r'magazinein contact with one surface of the :recording medium,.:a base, a second pole piece :carried by said :base, means'to mount said maga- W zineron said base, acoil encircling said second .;pole piece, and means to connect one end of said second'polepiece to said first pole piece to magnetically charge the latter, said last-named meanstbeing operablein response to assembly C5 ;;of said'magazine on'saidbase.

'7. In apparatus of the characterdescribed, a emagazine; a recording medium within said mag- "azine,.a pole piece within said magazine in con- "tact'with saidrecording medium, a base, a pole 7ozpiece 'carried by said base, guide means associated with=saidbase and magazine, respectively, toretainsaidmagazine in a predetermined positionm ith'respectrto said base, and means to shift said pole pieces relative to one another to op- 7 eratively :position saidtpole pieces withxrespect to one another and said recording medium, said Number last-named means being operable incident toen- 1,799,795 gagement of said guide means. 2,058,399 JOSEPH B. WAIAKER. 2,321,812 5 2,353,044 REFERENCES CITED n 2 359, 17 The following references are of record in the 21364556 file of this patent:

UNITED STATES PATENTS m Number Number Name Date 584,276

1,237,496 Funkhauser Aug; 21; 1917 Name Date Horton Apr. '7, 1931 Begun Oct. 27, 1936 Heller June 15, 1943 Kriegsheim July 4, 1944 Bryce Oct. 3, 1944 Somers Dec. 5, 1944 FOREIGN PATENTS Country Date Germany Sept. 16, 1933 

